1. Field of the Invention
The invention generally relates to the field of exercise machines and, more particularly, the invention relates to a multiple mode tug of war exercise machine useful in providing isometric, isotonic, isokinetic, and special accommodating resistance for continuous aerobic exercise.
2. Description of the Prior Art
Various devices have been developed both for testing and for exercising specific muscle groups. For example, in U.S. Pat. No. 4,674,741 to Pasierb, Jr. et al., an exercise rowing machine is disclosed which has a video display. The machine is intended to exercise and develop the user's legs, back, shoulders, arms, and other areas of the body without excessive stresses being applied, for example, to the knees.
In U.S. Pat. No. 4,822,036, an isokinetic exercise machine is disclosed which generates resistance that is a sum of two components: isotonic and isokinetic resistance. The isotonic component is independent of motion speed and the isokinetic increases with motion speed when the motion speed exceeds a pre-selected level. The machine includes a handle which can be held in the user's hand for creating a substantially downward directed pulling force. The patent mentions that the exercise can also be used to strengthen the legs and illustrates a combination of isotonic and isokinetic resistance.
An isokinetic exercise and monitoring machine is disclosed in U.S. Pat. No. 4,565,368. The machine described in this patent is primarily directed to an isokinetic exercise and monitoring machine for use in exercising and monitoring the back muscles of an individual. The upper portion of the individual's body, above his waist, is restrained by one restraining means while the individual's lower body, below his waist, is restrained by another restraining device.
U.S. Pat. No. 4,848,152 is primarily concerned with measuring a person's lifting capacity for determining a users maximum lifting capacity. For this purpose, the machine includes a handle and cable for user input. The user exerts force against the handle which is fixed to the cable, the person seeking to lift or pull the handle and cable in a substantially vertical upward direction. Dynamic testing techniques, of the type disclosed in this patent, are used to develop isokinetic exercise apparatus in which the user moves at a constant velocity regardless of the amount of resistance that is applied. A visual display has a CRT screen positioned for viewing by the user thereby achieving biofeedback to the user of the lifting technique. This patent also cites numerous other patents which disclose related constructions for operating in an isotonic (constant force) mode, isotonic or isometric modes; programmable acceleration, preselected acceleration and constant velocity patterns. The machine of the patent discloses a vertical lift device used as a means of assessing leg and back strength.